Sorry to hear you're struggling with such underpowered hardware. ;-) A little more information would be helpful, though:
1. What version of PG are you running? 2. What are the constraints on the child tables? 3. How many rows does each copy insert? 4. Are these wrapped in transactions? 5. are the child tables created at the same time the copies are taking place? In the same transaction? 6. Are the indexes in place on the child table(s) when the copies are running? Do they have to be to validate the data? 7. What are the configuration settings for the database? (Just the ones changed from the default, please.) 8. Which file system are you running for the database files? Mount options? 9. Are the WAL files on the same file system?
10. are you copying directly into the child tables or into the parent and then redirecting to child tables via a trigger?
